Mechanical stoker



E. LU

MECHAN APPLICATION NDGREN.

ICAL STOKER.

FILED JUNE I6. I9II.

Patented Feb. 14, 1922.

3 SHEETS SHEET l.

E'. LUNDGREN.

MECHANICAL STOKEH.

APPLICATIQN F1LEDJUNE16.19I1.

A THNELS 3 SHEETS-SHEET 2.

Patented Feb. 14, 1922.

l l /NVENTH E. LUNDGREN.

MECHANICAL STOKER.

APPLlcATIoN HLEDJuNE16,19x7.

' Patented Feb. 14, '1922.

3 SHEETS-SHEET 3.

' IN V EN TOR.

@MI-M4 (.l/

64M. a( BY MA/#Wm ATTORNEYS.

'unrrev arras PATENT GFFICE'.

' 'EDWN LUNDGREIT, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHO'USE ELETRC k82: MANUFACTURING COMPANY, A. CORPRAT'ION 0F PENNSYLVANIA.

MECHANICAL STOKER.

Meeres.

Specification of Letters Patent.

Patented Feb. 14C, 1922.

Applicatien filed June 16, 1917. Serial No. 175,202.

a specication.

This invention relates to mechanical stokers and especially to stokers of the in` clined type in which fuel moves from the front downwardly toward the rear of the furnace ase it passes through progressive stages of combustion.

It is well known that the capacity of a furnace is in a great measure limited bythe active grate area. By the' term active grate area I mean the area of the fuel supporting elements which are effective in delivering air,` for the purpose of maintaining combustion of the fuel supported on them.

An object of my invention is therefore the production of a mechanical stoker in which means are employed for increasing the active grate area.

A further object is to produce a dump grate mechanism, adapted for use in connection with mechanical stokers, in which improved means are employed for delivering air under pressure to the fuel supporting elements of the mechanism.

A. further object is to produce a dump grate mechanism in which new and irnproved means are employed for delivering air .under pressure to the mechanism and for cooling the' fuel supporting elements of the mechanism.

A further object is to produce a mechanical Stoker in which improved means are employed for var ing the air supply to different portions o the fuel bedmmaintained on the fuei supporting elements of the stoker, so that the stoker will operate with high efficiency throughout a wide range of loads.

These and other objects, which will be made apparent throughout the further description of the invention are attained by means of apparatus embodying the features` herein described and illustrated in the drawings accompanying and 'forming a part hereof.

iin the drawings: Fig. l is a iongtudinat sectional view of a Stoker embodying my invention taken along the line A-A of Fig. 2.

Fig. 2 is a plan view of the stoker illustrated in Fig. l.

Fig. 3 is a sectional view of a fuel supporting element forming a detail of the present invention. l Fig. l is a plan view of the element shown in Fig. 3.

Fig. 5 is a sectional View of the element illustrated in Fig. 3, shown in connection with cooperating supporting and air delivering elements.

Fig. 6 is a sectional view taken along the line 6-6 of Fig. 5.

Fig. 7 is a diagrammatic plan view illustrating the operative connections between the fuel feeding plunger and the reciprocating overfeed section which form details of the present invention.

Fig. 8 is a fragmental longitudinal sec-,

tional view of a modified form of dump grate mechanism which forms a part of my present invention.

Fig. 9 is a sectional view of an overfeed section forming a detail of the apparatus illustrated in Fig. 8.

The Stoker illustrated in Fig. l includes a hopper l0, to which fuel may be delivered by any suitable means. The hopper communicates with the ram box 1l, in which a ram 13 operates for the purpose of feeding fuel, discharged from the hopper, into the furnace, or onto the fuel supporting elements of the mechanical Stoker.

. The Stoker illustrated in Figs. l and 2 includes longitudinally arranged retorts le and combined fuel supporting and air delivering elements l5, which extend from the front downwardly toward the rear of the furnace and constitute the underfeed portion of the Stoker. Each retort is fed by one of the rams 13 and communicates at its upn per end with the discharge opening of the ram box. As illustrated, each retort consists of a floor 16 and the sidewalls or bars which support the elements l5. The elements l5 are illustrated as being made up of separate twyer blocks 17 located in overlao` ping relation' and each being provided with' air' delivery openings or passages adapted tov deliver air iaterally intt the fue as it issues* from the retorts. The twyer blocks are also provided with openings adapted to deliver air rearwardly and into and through the .fuel supported on the twyer blocks. 4The air delivered by the twyer blocks is received through a transversely extending air trunk 18, which communicates with and delivers air to the passages located between-the retorts and bridged by the twyerblocks 17. Fuel fed into the retorts by the rams 13 is forced out of the retorts and onto the twyer blocks by the continual fuel feeding action of the rams. This crowding action imparts a downward motion to the fuelconstituting the fuel bed.

In order to ensure complete combustion of the fuel issuing from the underfeed portion of the furnace, I have shown an overfeed portion made up of separate sections which are adapted to reciprocate and to aid the` lapping grate bars 23, which are mounted on the frame 20 and are locked in their mounting position by means of a locking member 24, which is detachably secured to and forms the rear end of the frame 20. As

, shown in Fig. 5, the bolt 24 extends through coacting lugs on members 2O and 24 to secure said members as a unit. Each grate bar extends'from the front to the rear edge of the frame, andits forward end is held in place by engagement with an inwardly projecting flange 26 formed on the frame. The rear end of each grate bar engages'a supporting and lock flange 26av formed on the locking member 24.

.Each grate bar 23, is formed in steps, and air ports 28, are formed near the base of each riser of each step. In order to prevent ash or other material from working back through these air ports and into the frame portion, I have provided a forwardly and upwardly projecting flange 29, which is located on the air admission side of each set of ports. The grates are also provided with longltudmally extending strengtheningl ribs 30, whlch serve the double purpose of preventing the bars from warping and at the same time provide ash retaining ocket's whlch protect the bars from the lilat ofi combustion within the i-re box.

, on the rod. l

The bracket 21,4 is also the As shown, the support 21 constitutes a .tially the direction of the plane of inclination of the fuel bed. In the apparatus illusg trated this motion is impartedto the separate sections of the overfeed portion xby means of rods 31 which are attached at'their lower ends to brackets 32 formed on or secured to the frames 20, and at their upper ends to the rams 13. An' adjustable -lost mo'- tion connection is employed between each soy ram and each rod, so'lthat the reciprocatory v justed to suit the'desiredconditions of fuel feed. The connection consists of a pin- 3 3, which is secured to the ram and which projects through slots formed in the ramguide.`

motion of the -overfeed ,sections may be ad The forward ends of. theV rods project4 through suitable openings formed in the pins, and the motion imparted toeach rod is dependent on ,the positionof an adjustable nut 34 with relation to a shoulder 35 formed' The fuel'from the located between it and the bridge 4wall ofthe overfeed section Vis -fedl i on to a dump 'grate mechanism, which is Y' furnace.` As illustrated in Figs. 1 and 2,A L

the mechanism is a double leaf dump mechanism, or includes two dump .grateslso arranged that the movable edges-of thel grates are adjacent `to each other.

The forward grate 47 ismounted on-thel` The construction grate bars 45 are removably mounted. f As I illustrated, the frame 48 is mounted` on a shaft 48a which is suitably journaled on the bracket 21. The forward edge o'f'the frame 48 is provided with a cylindrical face to accommodate the turning motion of the frame about theaxis of the shaft 48aV bars 45 `are removably secured to the frame by means of a removable lockingme'mberl The Agrate .y

and are similar in constructionto the bars 23. The means employed for securing these bars to the frame 48 is similar to the means@ .employed for frame k20.4

securingthe bars 23 to the The rear grate 52 ofthe dump grate inechl ansm is mounted 011 shaft 53,.which in turn is suitably mounted on the bridge wall'54. Both the grate 47 and the grate '52 are adapted to be swung downwardly, from the position sh'own in Fig. l, to substantially vertical positions for the purpose of dumpl' ing the accumulation of ash and clinkerde- Iivered to them from the overfeed: section. .l'b'

Lacasse The actuating mechanism of the grate 52 is -diagrammatically illustrated by means of a ratchet controlled level' 55, which is rigidly mounted on the shaft 53 and is located at one side of the furnace.

The operating mechanism of the dump grate 47,includes a suitably journaled shaft 56, a lever 57 rigidly mounted on the shaft and a link connectingthe free end of the lever to the free edge of the grate 47. It also includes a worm gear 58, located at one side ofthe ystoker and rigi-dly 'mounted on the shaft 56, and an actuating worm 59 which meshes with the worm gear. With this arrangement of operating mechanisms either the grate 47 or the grate 52 may be moved to the vertical or complete dumping position, or may be moved to intermediate positions between the dumping position and theposition shown in Fig. 1.

The dump grate 47 is provilded with an"l air delivery passage 61, which is located'between the grate bars 45 and the 'lower wall -of the frame 48. rThe grate bars 45, like the b ars 23, are in the form of steps, and the,

riser of each step is provided with a series of air delivery ports 46a which communicate with the passage 61 and whicharev adapted to deliver air to the fuel or mixture of fuel and ash on the dump grate. Air under pressure is delivered to the chamber 61 through ports 62, formed in the cylindrical face of the frame 48 and registering with correspondingly spaced ports formed in the bracket 21. The bracket 21 is provided with two air delivery passages 63 and- 64. The passage 63 delivers air yto i the grate bars-23 of the overfeed section through registering ports formed in the upper face of the bracket and in the lower face of the frame 20. The passage 64 communicates with the ports 62. Air under pressure is delivered to the passages 63 and 64 from the air duct 18, which receives air under pressure from a damper controlled conduit 65. A regulable damper 6 6 isinterposed betweenl the duct 18`and the inlet ends of the passages 63 and 64. In addition to this, each passage is provided with a separate controlling damper 67. .All these dampers may be controlled by suitable means located either at the front or side wall of the furnace and consequently the air supply to the to the overfeed section and tothe dump*- grate 47 may be controlled simultaneously with the control of air to the lower portion o1" the air suppliedto each of these fuel supporting elements may be controlled independently by adjusting the damper 66 and each of the dampers 67.

.In Fig. 8, I have illustrated a modifiedA arrangement of overfeed portion and dump grate mechanism. In this view the overfeed portion is mounted on the inclined face of the bracket 21 and consistsv of .a frame 68, which supports grate bars 69 located in overlapping relation from the front to the rear of the furnace.

These grate bars, unlike the bars 23, eX- tend transversely of the direction of the movement of the fuel across the overfeed section and are supported at their lateral edges by the upwardly projecting edges of the frame 68. The uppermost grate bar 69 is provided at each lateral edge with a depending L-sha-ped lug 70, each of which is adapted to engage an inwardly projecting The lowermost bar forms the locking member for the other bars. It isalso provided with the frame engaging lugs 70 but, inasmuch as these lugs are not engaged bythe rear edge of an adjacent grate bar, some means must be provided to prevent the bar moving with the fuel passing over the underfeed portion. As illustrated, each bottom grate bar is locked against downward movement by means of two pins 73, each of which passes through the fuel supporting face of the bar and engages one of the lugs 71- of\the frame. With this arrangement the grate bars 69 may be readily assembled on the frame and they may be as readily removed therefrom, since the pins 73 are in effect removable locking pins which hold the cooperating grate bars in place.

The grate bars and the frame form a hollow fuel `supporting element, the interior of which constitutes an air delivery passage. Air is delivered to this passage through a port 68a which registers with a port 74 formed in the frame supporting face of the 'bracket 21 and -communlcating with the passage 63 formed in the bracket. .The upper or fuel supporting faces -of the'bars 69 are corrugated, and the lower face at a point adjacent to the rear edge of eacl of the bars, with the exception' ofy the lowermost bar, is also corrugated, sothat these lower roo ima

corrugations form airV delivering passa es which receive air from-.the air passage ocated within the frame 6 8. The lowerinost lgrate bar is provided at its rear and with a downwardly turned nose 715, having ports- 75*l formed therein which receive ailfrom the interior of the frame. i y The dump grate mechanism illustrated in idly secured to the lowermost grate bar and to the frame 76. The operating mechanism of each grate is similar to the operating mechanism described in connection with the grate 47 of Fig. 1. Air is delivered to the forward grate as described in connection Hwith the grate 47 through the passage 64 formed in the bracket 21. In Fig. 8, the arrangement of the air ports 62 is more clearly illustrated and it will be apparent that these ports p move into register with ports 79 formed in the bracket and communicating with the passage 64 when-the grate is raised to the fuel supporting position illustrated in Fig. 8. The rear grate receives air from an 'air passage 80 built into the bridge wall 54.

The construction of this passage 80 is similar to that of the passage 64 and air is delivered to this grate in substantially the same way-that it is delivered to the forward grate of the dump mechanism.

It will be understood that for convenience of assembling, the overfeed portion of the furnace is assembled in sections which are substantially equal in width to the distance between retort centers. Each of these sections includes one of the frames 68 in lapparatusillustrated in Fig. 8, or one of the frames 20 in apparatus illustrated in Figs. l1 and 2. These sections are consequently independently movable and inasmuch as the 'fuel feeding rams to which. they are individually operatively connected do not move in unison, it will be apparent that some of the sections are moving in one direction' while others are moving in the reverse direction.

for convenienceV of assembling the dump grate mechanism is also divided into sections, each of whichfincludes a frame and its supported grate bars. These sections are preferably of the same width as the sections ofthe overfeed portion of the furnace and in wide furnaces it is desirable to divide them so as to form two or more dump grate -.mechanisms,le ach of which is independently operable.

I have describedl and illustrated several-.embodiments of .my invention, it Willi' be apparent to those skilled 'in the art that various changes, modifications, additions, and omissions may be made in the apparatus described and illustrated withoutdeparting from the spirit and scope of the invention, as setforth by the appended claims.

What I claim is:

1. Incombination with a progressive feed furnace grate, a discharge mechanism at the lower edge of the grate comprising a hollow swinging dump grate having an air chamber therein adapted to supply air at the dump grate surface, an air supply chamber adjacent the dump grate, and means along the lateral edge of the dump grate for receiving air from the supply chamber.

2. In combination with a progressive feed furnace, an ash discharge apparatus at the rear of the furnace comprisinghollow dump grates pivotally mounted at one edge, anl

air distributing chamber adjacent the dump grates at the pivoted edges, detachably secured grate lbars arranged to form airadmitting fuel-supporting surfaces of the-` dumpates, and means for delivering air from t e air distributing chamber tothe hollow dump grates.

8. In combination in a mechanical Stoker, an underfeed portion, an overfeed'portion receiving fuel therefrom, consisting of relatively movable frame members reciprocable in substantially the line of travel of the fuel, a dump mechanism for receiving the fuel delivered from the overfeed section and comprising a hollow swinging grate having air delivery passages formed in the upper wall `draft to the interior of said grates and the overfeed grate sections, and means for automatically shutting off the air to the dump For convenience of manufacture and also grate when Isaid grate is discharging clinker5 and ralla',

IIO

v6. In combination in an inclined under-4 feed stoker, a plurality of inclined retorts alternating with rows of air supplying means, means for feeding fuel into said retorts, a series of independently movable overfeed grate sections having air delivery passages therein, and a dump grate having an air delivery passage formed therein, means for delivering forced draft through said air supplying means, through said air delivery passages of the overfeed grate sections and through the air delivery passa-ge of said dump grate to the fuel bed, and means for controlling the delivery of forced draft through each of said elements.

7. In combination in astoker, a swinging double leaf dump grate mechanism comprising oppositely disposed hollow grates each having air delivery passages in the fuel supporting walls thereof, means for delivering forced draft under pressure to the interior of said hollow grates, and means for shutting off the supply of air when the dump grlate mechanism is-discharging clinker and as 8. In combination in a Stoker, a plurality of inclined retorts alternating with rows` of air supplying means, means for feeding fuel into said retorts, a. series of relatively movable overfeed` grate sections having air delivery passages therein, regulable means for imparting motion to each grate Section, a dump grate mechanism receiving fuel from the grate sections, independently regulable means for delivering air under pressure through' said air supplying means, the said air delivery passa es in the underfeed grate sections and said ump grate to the fuel bed.

9. In combination with an underfeed stoker, an inclined overfeed grate adapted to receive fuel from the underfeed portion of the Stoker, a hollow ash discharge mechanism' at the lower end of the overfeed grate, said overfeed grate consisting of a frame having a bottom portion and side and end portions arranged to form an air chamber, detachable grate bars having air delivery passages therein supported upon the side and end portions, means for locking said bars to said side and end portions, means for independently delivering air under pressure to said chamber and the discharge mechanism and means -for diminishing and shutting of the supply of air to the dump grate when the latter is lowered to discharge clinker and ash.

10. In combination in an underfeed Stoker, an inclined underfeed grate, a hollow swin 'ng dump plate for receiving fuel and ash rom the overfeed grate, and means for separate] delivering air to the interior of the overfeed grate and the interior of the dump plate.

11. In combination in a stoker, an underfeed section, an overfeed section, and a dump grate successively receiving fuel to be burned and each provided with air passages for delivering air to the fuel, means for de livering air under pressure to air passages of each of the sections and the dump grate, means for separately controlling the delivery of air to the overfeed section and the dump grate, and means for jointly controlling the delivery of air to the overfeed section and the dump grate.

12. In combination in a Stoker, a double leaf hollow swinging dump rate, each leaf having an air inlet port, am? a plurality of air delivery ports, and means for delivering air under pressure to each leaf and for cutting off the supply of air when the grate is swung to its lowest position.

13. Stoking mechanism comprising in combination a supportin grate, a hollow dump grate cooperating t erewith provided with an air admission port and adapted to be swun into open position, an air chamber provider? with a port adapted to register with the port in the dump grate when the dump grate is in closed position and to be closed by the dump grate when the said grate` is swung into open position.

14. In combination in a Stoker, a swinging dump ate mechanism comprising a hollow ate avin air delivery passages in the uel supportin walls thereof, means for delivering force draft under pressure to the interior of said hollow gra-te, and means for automatically shutting off the supply of air when the dump grate mechanism is discharging clinker and ash.

15.l In combination in an underfeed Stoker, an inclined underfeed grate, a hollow reciprocable overfeed lgrate receivin fuel and ash from the underfeed rate, a ollow swin ing dump plate for receiving fuel and ash om the overfeed rate, and means for separately controlling t e delivery of air to the interior of the overfeed grate and to the interior of the dump plate.

In testimony whereof, I have hereunto subcribed my name this 9th day of June, 191

EDWIN LUNDGREN.

Witnesses:

C. W. MCGHEE, E. W. MoCAmsfmR. 

